About the initial payment.

Hi,
It might seem to be a silly question, but nowhere else has it been mentioned as far as I know, so I'm just asking here.
About the initial payment made when I first created a droplet, is it sort of a deposit? It seems that the billing process is like 1)make a payment 2) create a droplet 3) I get billed for the amount of hours while my droplet has been running for 28 days 4) paid 5) another billing cycle starts 6) After 28days, I get billed for the 28days of usage on hourly basis .......etc....etc....
So, is the initial payment, whichever the cost shown in the pricing menu, a one-time payment and from the second billing cycle, it doesn't recur? Do I understand correctly?